I have the acoustimass 10 Bose system and thinking about mounting the speakers (Front) on the TV wall up 7/8 feet in corner of room? Is it not wise to do so? Will I hear a quality difference?

Ideally, it is best to install your speakers with the tweeters at ear level when seated. With speakers that high up, the sound will never seem to be coming form the TV, but somewhere above it, which to me is very unnatural.

Of course lots of people like to mount their TV too high on the wall as well. Go figure.

I'd suggest not putting them in the corner at any height. When you cup your hands around your mouth and speak, you'll hear what the corner will do to your speaker's sound. Speakers need to be out in the open to sound their best, unless they were designed specifically to be placed near (or on or in) a wall. I'm not familiar with Bose's recommendation for placement, but I would be very surprised if placing them in a right tricorner would be acceptable. If they have to be mounted on a wall surface, at least put them to the right and left of your TV screen and not way up high.

I have the acoustimass 10 Bose system and thinking about mounting the speakers (Front) on the TV wall up 7/8 feet in corner of room? Is it not wise to do so? Will I hear a quality difference?

Can you still return the Bose and buy some good speakers? If you must use the Bose, mounting your speakers at ear level will be much better than near the ceiling. Good luck.